Electric lamp and similar devices



May 23, 1939. I w, H N r AL 2,159,794

ELECTRIC LAMP AND SIMILAR DEVICES Filed April 22, 1938 Ihvencofs: Wi\he\m Hagen,

Wolfgang Thourec, Josef Kern, by 1 515 M he'n Attorney.

Patented May 23, 1939 2,159,794

UNITED STATES PATENT OFFICE ELECTRIC LAMP AND SIMILAR, DEVICES Wilhelm Hagen, Berlin, Wolfgang Thouret, Berlin-Wilmersdorf, and Josef Kern, Berlin, Germany, assignors to General Electric Company, a corporation of New York Application April 22, 1938, Serial No. 203,690 In Germany April 29, 1937 3 Claims. (Cl. 176-38) Our invention relates to electric lamps and ward against the contracting external stem tube similar devices generally, and more particularly so that the ribbons are embedded under pressure. to a seal for the leading-in conductors, especial- Where a tube is arranged axially within the ly where the said leading-in conductors are sealed stem tube it may, if desired, constitute the exhaust in quartz or a high silica glass similar to quartz. tube of the bulb, particularly where the bulb is It has been suggested heretofore that in order filled with gases. However, if desired, an addito obtain a thermally and mechanically strong tional leading-in conductor, for example a fine hermetic seal of conductors in quartz or high tungsten wire, may be sealed into the axis of the silica glass the said conductors be made in the stem tube. In certain instances, if may also be form of extremely thin ribbons or foils, particdesirable to flatten the axially disposed rod or 10 ularly molybdenum foils having a thickness of tube at the points where the ribbons are located, less than 20 microns. Tests have shown that or to employ a rod or tube of prismatic shape, with such foil or ribbon conductors it is possible for example a flat rectangular rod with the ribto obtain, by properly designing the seal, single bon arranged on each of the wide sides.

ended electric incandescent lamps, particularly For a further understanding of our invention, 15 projection lamps carrying a high load, which are reference may be had to the drawing in which easy to manufacture and will withstand high Figs. 1 and 2 are elevations, in section, of two stresses. forms of incandescent lamps comprising our According to our invention the incandescent invent onelectric lamp comprises a bulb of quartz or glass The projection a p s ow in 1 COmDIiSES 20 with a high silicic acid content havin an outa h avy-Wa l d bulb l of quartz seeded to the wardly extending stem or neck portion in which annular flange 2 of an outwardly extending Stem the ribbon-like conductors are sealed, preferably Comprising a quartz stem tube 3 and an axially between a rod or tube and a surrounding stem arran inn r q z u e 4- Thin rib ons or tube which may be the neck portion of the bulb. f ils 5-5 f refractory metal. such as molybde- 25 In the manufacture of these lamp the ibb num for example, are sealed between said tubes are inserted in the narrow annular gap between 3 d 4 and s v s e leading-in Conductors the stem tube and the axially disposed rod or together with our lead wires 6, l and inner lead tube, the said annular gap is evacuated and the and pp es 9 COIineeted t0 he ends stem tube, and consequently also the axial tube, theieof- A filament is upported by and con- 30 is heated by means of external flam whereby nected at its ends to said inner lead wires 8, 9. the softened stem tube is pressed tightly against The Outer lead W es are Con e ed to a the ribbons which are held in position and supscrew thread Contact 6 and n d Contact ported by the axial rod or tube, while the other of metal p w r x mpl on a ceramic base points of the stem tube melt and form a cylin- H which surrounds the stem 4 and s attached 35 drical body together with said rod or tube. The thereto by Cement A pp t W s new lamp construction is particularly advanta- Sealed into the pp n er end o tube 4 and geous for high intensity projection lamps, serves as an additional support for the filament pecially those lamps containing a filling of a 40 chemically inert gas or vapor such as mercury The device shown in Fig. 2 is a high-pressure 40 vapor or mixtures thereof at high pressures of mercury p comprising a q r z bulb l3, the above one atm s h r for examp1e neck portion I3 of which surrounds a small A particularly good ,1 is obtained when a quartz tube l4 closed at both ends, said neck porcounter pressure is produced within the axially iiOn d tube l4 Comprising an outwardly disposed tube during the sealing process. This tending stem- The molybdenum s p foils 45 pressure may be produced for example, by con.- l5|5 which serve as portions Of lead-in COl'ld'llC- necting the tub t a high pressure i or by tors are sealed between the axial tube I 4 and employing a tube which is closed at both ends bulb neck A filament extends axially of and contains a gas or vapor filling of such quanth u l3 a d s DD at s ends y inner tity that the heating which occurs during the l ad-in W r s l7 a -in W r i1 havin 50 sealing produces the desired gas or vapor presthereon an insulating Cover such as a sure. The amount of pressure is so controlled t eous ube. e bu b l3 Contains a gaseous that even when a thin-walled tube is used, 001- filling comprising rare gases or nitrogen or mixlapsing of the soft tube wall is avoided and up tures thereof and also a small quantity of merto a certain extent the tube wall is pressed outcury H] which, during operation, may be com- 55 pletely vaporized and which supplies the desired high vapor pressure of, for instance, ten atmospheres.

When it is desired to use the tube i l or t for evacuation and gas filling of the bulb, the upper or inner end thereof is left open, and the lower or outer end thereof is sealed in the usual manner after the bulb has been filled with the desired gas or vapor. During the sealingin of the lead-in conductors a pressure may be produced within the tube M or l by closing both ends of said tube after it has been filled with a suitable quantity of gas or vapor so as to develop the desired pressure when heated by the sealing flames. Support wires such as wire l2 may also be employed for supporting other internal elements, such as a reflector arranged behind the filament. Also, if desired, an additional lead-in conductor may be extended axially through tube t or M,

What we claim as new and desire to secure by Letters Patent of the United States is:

1. A high-intensity electric larnp compr sing a bulb of high-silica vitreous material contan light source, a stern of high-silica vitreous rial extending outwardly from said bulb and cor-lprising a stern tube and an inner tube extending axially of said stem tube, lead-in conductors of thin refractory metal extending along and fused in said stein between said tubes, and inner lead-in conductors connected to said first-mentioned conductors and to said light source, said inner tube being sealed at both ends and containing a gaseous filling used for creating a pressure in said tube during the sealing-in of said first-n1entioned lead-in conductors.

2. The method of manufacturing a stem which comprises assembling a vitreous stem tube, a vitreous inner tube extending axially within said stem tube and sealed at both ends with a gaseous filling therein, and lead-in conductors extending longitudinally between said tubes, and then ap-- plying heat to fuse said tubes together with the said leading-in conductors sealed therebetween, the gaseous filling in said inner tube being expaneled by the heat to exert a pressure expanding the walls of said tube against said lead-in conductors and the surrounding stern tube.

3. An electric lamp comprising a bulb of vitreous material containing a light source, a stem of vitreous material at an end of said bulb comprising a stem tube and an inner tube extending axially of said stem tube, and lead-in conductors having portions extending along and fused in said stem between said tubes, said conductors extending into said bulb to said light source, said inner tube being sealed at both ends and containing a gaseous filling used for creating a pressure in said tube during the sealing-in of said lead-in conductors.

WILHELM HAGEN. WOLFGANG THOURET. JOSEF KERN. 

